Larger Benthic Foraminifera and Microfacies of Late Paleocene - Early Eocene Sections in Meghalaya, Northeast India

Abstract

The Late Paleocene-Early Eocene sections from Lakadong Limestone (Mawmluh Quarry) and Umlatdoh Limestone (Komorrah Quarry) in Meghalaya, Northeast India were examined for larger benthic foraminiferal microfacies and carbon isotopes. We generated high-resolution age models using larger benthic foraminifera biostratigraphy and recorded the change in microfacies. The LBF microfacies in SBZ 3 (∼58–60.7 Ma) and SBZ 4 (56–58Ma) is dominated by Miscellanea, Glomalveolina, Ranikothalia, orthophragminids, dasycladalean green algae and coralline red algae, indicating that deposition occurred within inner to mid-ramp environments. An abrupt shift in the depositional setting from open marine Lakadong Limestone to restricted marine Lakadong Sandstone across the PETM possibly indicates major changes in hydrological cycle during the extreme warmth that followed the PETM. The marine sedimentation continued during the Early Eocene (SBZ 7–9 corresponding to 55.1–52.8 Ma) within Meghalaya that led to the formation of Umlatdoh Limestone dominated by Halimeda, Alveolina, and miliolids. The larger foraminiferal extinction and origination in the Meghalaya basin is marked by the extinction of late Palaeocene Ranikothalids, Glomalveolinids, dominating the Lakadong Limestone and the dominance of Alveolinids and Discocylinids in the early Eocene Umlatdoh Limestone.